[Expat-discuss] Handling Error Conditions in Callbacks

[Nick MacDonald]

Jim:

User Data is just for code written by you, the user.  It is not
examined in any way by the eXpat parsing routines.  If you find an
error in your code that is being called to interpret the data (you
don't like the input, but it is still valid, well formed XML) then you
will need to set your own error handling variables and your own
routines will need to ignore the input.  For example, say you are in
the middle of reading tag <X> and a sub tag is wrong, and you want to
ignore tag <X> and all the sub tags, you need to code logic to tell
all the call back routines to ignore input until you see the proper
</X> close tag.

If the XML is not valid, eXpat will inform your code via call backs
and error returns.  You don't have to do anything special here, other
than clean up your data at the end (if you don't intend to act on
partial/invalid data.)

If you want to abort processing in the middle because you don't like
the input so far, then there is an eXpat function you can call from a
call back that will achieve this for you.

Good luck,
  Nick

On Feb 8, 2008 11:17 AM, Themis, Jim <jthemis at ti.com> wrote:
> I am working on my first XML project, therefore my first experience with
> expat.  I had a question how other are dealing with error conditions
> within their callback handlers.  Since the callbacks provide no return
> value, I assume, one could use the UserData to store the error condition
> and pop that up  the callback stack.  Just wanted to make sure I wasn't
> missing any functionality within expat.